Conventional processes for extracting palm oil utilize significant quantities of water and energy and result in a substantial amount of Palm Oil Mill Effluent (POME) and waste water. Conventionally, palm fruit bunches are sterilized and cooked as an initial process. The sterilization and cooking of palm oil fruits is carried out using saturated steam of 100° C. at atmospheric pressure generated from a boiler or furnace. The conventional process uses large amount of water to generate the steam to sterilize the fruits. The time needed for cooking is approximately 1 hour. Then the cooked/sterilized fruits are transferred to a stripper or thresher to break apart fruit bunches and break open the skin of the fruit.
There are several problems associated with the conventional sterilization process. One problem is that it is a wet process, so water consumption is high. Energy consumption is also high because steam has to be generated. Another problem is that large amounts of waste water are generated, and the waste water contains solid and liquid materials that cause pollution problems including greenhouse emissions. Another disadvantage is that the process time is high and the later step of stripping or threshing causes noise and vibration.
After sterilization and stripping/threshing, the conventional palm oil process presses the fruit to extract palm oil and then filters the palm oil. The filtered palm oil is then clarified using a tank and mixing in hot water. The clarification tank is kept at a high temperature ranging from 80° C. to 90° C. by a heating coil and continuous injection of steam to maintain the water levels. Generally, the clarification tank will have a palm oil emulsion to water ratio of 1:3 to 1:5. When the emulsion is introduced to the clarifier tank, it is stirred within the tank for the emulsion to be diluted by the hot water and to separate the oil molecules from the water molecules, which thereafter float to the top of the tank where there is a skimmer or an overflow pipe to collect the crude palm oil. The time it takes for the oil to float up and be collected ranges from 3 to 5 hours.
After the skimming or overflow process, the crude palm oil will still have water and suspended solids, which are removed by a centrifugal decanter system. The dried oil is processed through a vacuum drier to remove any moisture up to the specifications as required by the refineries. The water from the emulsion and the suspended solids are mixed with water and are discharged as sludge periodically and may be treated in a three phase decanter process and channeled to holding tanks and subsequently to effluent ponds around the oil mill as Palm Oil Mill Effluent (POME) together with the waste water from the sterilizer section and other sections of the mill.
The conventional clarification process also has several disadvantages. Water and energy consumption is high because of the need to maintain the water temperature for long periods of time and to power the downstream processes used to remove residual water. These are complicated processes that require significant space at the mill and high maintenance as well as causing noise and vibration. The water-based clarification process produces significant amounts of Palm Oil Mill Effluent (POME), which requires big tracts of land for effluent ponds for treatment. Another disadvantage is the significant loss of crude palm oil through the discharge of the POME.